1. Technical Field
The present invention relates to fluid heating devices for heating a fluid, such as for example regenerative pumps that can be utilized to circulate and heat a coolant in a vehicle air conditioning/heating system.
2. Description of the Related Art
U.S. Pat. No. 3,720,372 discloses a known fluid heating device that includes a throttle valve disposed downstream of a pump. The fluid pressurized by the pump is introduced to the throttle valve and the throttle valve brakes the fluid in order to heat the fluid. As shown in FIG. 7, the pump 110 of U.S. Pat. No. 3,720,372 has a suction port 113, a discharge port 114, a housing 111, a rotor (impeller) 120, blades (radially extending walls) 121 and channels (grooves) 123. The rotor 120 rotates together with blades 121 within the housing 111. The blades 121 and the channels 123 extend radially from the rotational center or axis 122 of the rotor 120. The housing 111 includes a dividing wall 115 that separates the suction port 113 from the discharge port 114. As shown in FIG. 8, surface 126 of each channel 123 has a curved or semi-circular shape. The outer circumference end 126a and the inner circumference end 126b of the channel surface 126 have equal heights H from the base of the channel 123. Further, the outer circumferential end 126a of the channel 123 forms a wall portion 124 that shields the channel 123. When the rotor 120 rotates, the fluid drawn from the suction port 113 is pressurized and released from the discharge port 114. The throttle valve (not shown) is disposed downstream of the discharge port 114 and the throttle valve brakes the flow of fluid. By throttling or braking the fluid, the internal energy of the fluid is converted to heat and the fluid temperature increases.
It is an object of the present invention to provide improved fluid heating devices. For example, fluid heating devices of the present teachings may heat the fluid more efficiently than the known fluid heating device. In one embodiment, the fluid heating device may include an improved rotor for pressurizing the fluid. The rotor may include a rotor body, blades and channels. The rotor body may be rotatably supported within a rotor housing. The blades are provided on the circumferential surface of the rotor body. The blade of the rotating rotor pressurizes a fluid drawn into the rotor housing. The pressurized fluid may then be throttled or braked in order to generate heat that will increase the fluid temperature. The channels may be provided on the circumferential surface of the rotor body such that one channel is formed or defined between each two adjacent blades. The height of at least one channel at the inner circumferential end is preferably greater than the height of the channel at the outer circumferential end, which has the effect of increasing the fluid temperature more efficiently.
Other objects, features and advantage of the present invention will be readily understood after reading the following detailed description together with the accompanying drawings and the claims.